The present invention generally relates to the fabrication of shell formed bodies, and the invention is particularly directed to the fabrication of integral shell formed bodies from a number of elongated panels which each along one longitudinal edge has a substantially U-formed groove and along opposite longitudinal edge has a rib or tongue for intermeshing the groove portion.
By shell formed body is meant in this connection any type of body whether shell or plate like and whether plane of curved. The expression is intended to include even bodies like pipes, containers, building structures, boats, ships, air planes etc.
The invention is intended for the fabrication of all kinds of shell-formed elements like walls, roofs or ceilings, floors etc. of buildings, shells, shelves, partition walls etc. of furniture or building components and many other purposes.
A special field within which the invention can be applied and is suitable is the fabrication of different parts of ships and small boats, for instance hulls, decks, bulkheads and plates, etc.
The invention also generally relates to a hull construction by what is meant in this connection any type of an integral and preferably sealed body.
The shell formed elements according to the invention may be fabricated from any conventional material but the invention is especially suited for use of plastic or any metal, in particular aluminum.
Integral shell-formed elements previously used to be fabricated from elongated panels of wood having groove and tongue connection means. Such shell formed elements generally necessitate some transverse joining element like a cross-rib for interconnecting the different panels. Also for giving the groove and tongue connection means sufficient strength the panel as an entire object has to be over-dimensioned. Such a structure therefore is heavy and bulky.
In turn, shell formed bodies of plastic, iron, aluminum or any other metal generally are fabricated by rivetting or welding narrow panels together. Riveting is a time consuming and expensive operation whereby it is necessary to either join the panels by overlapping joints or to use a special joining rib extending across the joint. For obtaining a sufficient strength and seal a very large number of rivets must be used. When welding panels a weakened zone of the panel is generally obtained aside of the weld. Usually it is therefore necessary to over-dimension the material of the entire panel considering the strength of the weakest portion of the material. Often welding also gives heat strains which may provide weakened portions or stretchings or buckles of the welded panels. Therefore also welded or riveted constructions become heavy, uneven and un-necessarily expensive.
Attempts also have been made to join panels by gluing same together, but also in such cases it was thought that the joining had to be made by an overlap joint or by means of overlapping joining connections. Also, the gluing was not considered to give the same safety as a mechanical joint.
Panels of the above mentioned type can be made by molding or milling etc. but most economically they are generally made by extrusion. The panels may be of any suitable material which has sufficient bending and rupture strength to be suited as a hull material and as example of suitable materials may be mentioned different types of wood, platic, steel or some other metal. A specially suitable material is aluminum. By "hull" is in the present connection meant any type of an integral body which completely or partly is convexly formed at the exterior. The invention is suited for fabrication of different types of hull-structures like containers, resevoires and tubes etc. The invention is, however, especially suited for the fabrication of conveyances, especially fabrication of bodies for boats, airplanes, air-ships etc. where there are strong demands from the body structure to be water or gas proof, to have a low weight and to have great strength. In the following the invention therefore will mainly be described with reference to the fabrication of hull structures for boats etc., but it is to be understood that such description is only of examplifying nature and is not restricting the invention.
There are several principal methods of making hull structures. Hulls may be made by molding or baking in a concave mold or on a convex plug as for instance when fabricating plastic material boats. In such case, however, the size and form of the mold completely restricts the hull type. During molding often health endangering vapors appear, and the work often is rather time pressed since the molding generally must be made at least substantially continuously and at particular temperatures and climatic conditions.
A previous usual method of fabricating hull structures especially for boats is to join a large number of narrow boards of wood by riveting same and sometimes also gluing same generally with the assistance of frames. Also this method of making hull structures is time consuming and expensive both since the boards must be carefully formed according to the hull type, generally so that they are wider amidships than at the stem or stems and since a large number of rivets must be used. Also in this type of making hull structures there are some restrictions to a predetermined form and size of the hull. Also, in order to get a sufficient strength the hull becomes rather heavy in relation to the volume or buoyancy thereof.
The object of the invention therefore is to solve the problem of fabricating an integral shell formed body or hull structure from a number of elongated panels, the material of which need not be overdimensioned, which can be joined so that the surface of the body becomes even, which gives a completely sealed body, where the panels and thereby the shell formed body or hull structure is light but still strong and cheap to fabricate, and where the panels are flexible and may be adapted to different purposes. The method offers a great freedom in choice of fabricating method and enables within wide limits changes and reconstructions during the building of the hull, it allows fabrication of practically any form and type of hull, and the method is so simple that it is well suited even for non-experts to build hull structures.